title: Increased risk of intraoperative awareness in patients with a history of awareness.
abstract: BACKGROUND
  Patients with a history of intraoperative awareness with explicit recall (AWR) are hypothesized to be at higher risk for AWR than the general surgical population. In this study, the authors assessed whether patients with a history of AWR (1) are actually at higher risk for AWR; (2) receive different anesthetic management; and (3) are relatively resistant to the hypnotic actions of volatile anesthetics.
  
  
  METHODS
  Patients with a history of AWR and matched controls from three randomized clinical trials investigating prevention of AWR were compared for relative risk of AWR. Anesthetic management was compared with the use of the Hotelling's T statistic. A linear mixed model, including previously identified covariates, assessed the effects of a history of AWR on the relationship between end-tidal anesthetic concentration and bispectral index.
  
  
  RESULTS
  The incidence of AWR was 1.7% (4 of 241) in patients with a history of AWR and 0.3% (4 of 1,205) in control patients (relative risk = 5.0; 95% CI, 1.3-19.9). Anesthetic management did not differ between cohorts, but there was a significant effect of a history of AWR on the end-tidal anesthetic concentration versus bispectral index relationship.
  
  
  CONCLUSIONS
  Surgical patients with a history of AWR are five times more likely to experience AWR than similar patients without a history of AWR. Further consideration should be given to modifying perioperative care and postoperative evaluation of patients with a history of AWR.
authors.affiliation: * Medical Student and Predoctoral Research Trainee, Division of Cardiothoracic Anesthesiology and Department of Anesthesiology, ‖ Assistant Professor of Anesthesiology, Department of Anesthesiology, §§ Professor, Division Chief, and Director of INQUIRI, Division of Cardiothoracic Anesthesiology, Washington University School of Medicine, Saint Louis, Missouri. † Research Assistant Professor, ‡‡ Henry E. Mallinckrodt Professor and Department Head, University School of Medicine, Saint Louis, Missouri. ‡ Assistant Professor, Division of Biostatistics, Department of Mathematics, Washington University in Saint Louis, Saint Louis, Missouri. § Statistician Lead, ‖‖ Associate Chair for Faculty Affairs; Associate Professor of Anesthesiology and Neurosurgery; Faculty, Neuroscience Graduate Program, Department of Anesthesiology, University of Michigan Medical School, Ann Arbor, Michigan. # Associate Professor of Anesthesia and Critical Care, Department of Anesthesiology, University of Chicago, Chicago, Illinois. ** Professor and Department Head, †† Research Technician, Department of Anesthesiology and Perioperative Medicine, Faculty of Medicine, University of Manitoba, Winnipeg, Manitoba, Canada.
authors.forename: Amrita
authors.initials: A
authors.lastname: Aranake
authors.forename: Stephen
authors.initials: S
authors.lastname: Gradwohl
authors.forename: Arbi
authors.initials: A
authors.lastname: Ben-Abdallah
authors.forename: Nan
authors.initials: N
authors.lastname: Lin
authors.forename: Amy
authors.initials: A
authors.lastname: Shanks
authors.forename: Daniel L
authors.initials: DL
authors.lastname: Helsten
authors.forename: David B
authors.initials: DB
authors.lastname: Glick
authors.forename: Eric
authors.initials: E
authors.lastname: Jacobsohn
authors.forename: Alex J
authors.initials: AJ
authors.lastname: Villafranca
authors.forename: Alex S
authors.initials: AS
authors.lastname: Evers
authors.forename: Michael S
authors.initials: MS
authors.lastname: Avidan
authors.forename: George A
authors.initials: GA
authors.lastname: Mashour
mesh_terms: D000328:Adult; D000368:Aged; D000758:Anesthesia / Q000379:methods; D000777:Anesthetics / Q000493:pharmacokinetics; D018685:Anesthetics, Inhalation; D015331:Cohort Studies; D015897:Comorbidity; D056805:Consciousness Monitors; D003627:Data Interpretation, Statistical; D004351:Drug Resistance; D005260:Female; D006801:Humans; D058926:Intraoperative Awareness / Q000453:epidemiology*; D016014:Linear Models; D008297:Male; D008568:Memory; D008875:Middle Aged; D012008:Recurrence; D012306:Risk; D012307:Risk Factors; D016896:Treatment Outcome
chemical_list: D000777:Anesthetics; D018685:Anesthetics, Inhalation